Insulation system and method

ABSTRACT

An insulation system for a cavity of a building structure, including: a layer of plastic foam insulation present on a substrate of the cavity, and a layer of blown-in fiberglass insulation in substantial contact with the layer of plastic foam insulation, wherein the layer of plastic foam insulation is present between the substrate and the layer of blown-in fiberglass insulation.

BACKGROUND

In the construction of residential and commercial buildings, the use ofan unvented attic can provide enhanced energy efficiency performance andan improved resistance to adverse weather conditions. In an unventedattic, the thermal and moisture control boundary is typically present atthe plane of the roof deck, as opposed to the ceiling of the livingspace as in a conventional attic. Since the unvented attic constitutes apart of the conditioned area of the building, thermal leakage emanatingfrom HVAC equipment and/or ductwork present in the attic is transferredto and from the conditioned space. As such, energy losses due to thermalleakage in the HVAC system can be reduced or eliminated by the use ofthe unvented attic.

In the construction of an unvented attic, a polyurethane spray foaminsulation can be used to provide thermal insulation and management ofair infiltration and/or moisture migration. Use of such polyurethanespray foam facilitates construction of the unvented attic, and the sprayfoam typically can be applied to the interior surface of the roof deck.However, polyurethane spray foam is generally a flammable material.

It has been proposed that an ignition barrier or thermal fire barrierover the polyurethane spray foam insulation is typically not required insituations where the unvented attic is accessed only for maintenancepurposes. However, unvented attics may find use as additional storagespace, and therefore such unvented attics may be accessed morefrequently, thereby increasing the risk of fire originating in theattic.

SUMMARY

According to one aspect, an insulation system for a cavity of a buildingstructure is provided, comprising:

a layer of plastic foam insulation present on a substrate of the cavity,and

a layer of blown-in fiberglass insulation in substantial contact withthe layer of plastic foam insulation,

wherein the layer of plastic foam insulation is present between thesubstrate and the layer of blown-in fiberglass insulation.

According to another aspect, a method of insulating a cavity of abuilding structure is provided, comprising:

forming a layer of plastic foam insulation on a substrate of the cavity,and

forming a layer of blown-in fiberglass insulation such that the layer ofblown-in fiberglass insulation is in substantial contact with the layerof plastic foam insulation,

wherein the layer of blown-in fiberglass insulation is arranged at aninterior side with respect to the layer of plastic foam insulation.

DETAILED DESCRIPTION

The methods and systems can be used to insulate any building structureor feature including, for example, a cavity such as a cavity of a wall,attic or crawl space. The cavity can constitute a space defined by twoadjacent supporting members of a building such as studs or trusses, anda backing substrate arranged between such supporting structures. Forexample, the supporting members can include, but are not limited to,natural lumber, engineered wood, metal, and composite building productsof various dimensions. The backing substrate substrates can include, butis not limited to, oriented strand board, plywood, hardboard, metaldecking, corrugated metal panels, natural lumber, poured concrete orprefabricated concrete.

Attics can be built using various techniques and the shape and structureof attics can vary widely. For example, attic cavities can be regularlyor irregularly shaped and in an exemplary embodiment, use of the methodsand systems can facilitate the insulation and sealing of irregularlyshaped cavities and structures typically found in attics.

A plastic foam layer is formed on a substrate of the wall or atticcavity. The plastic foam layer can provide thermal and/or acousticinsulation, and optionally function as a moisture vapor retarder and airbarrier. The plastic foam can be semi-rigid or rigid and can include afoam insulating board such as Dow Styrofoam insulation board, or apolyurethane spray foam. In an exemplary embodiment, the plastic foamincludes a polyurethane spray foam.

For example, the polyurethane spray foam can be applied to the substrateby any suitable method, for example, by the on-site mixing of at leasttwo foam components, spraying the mixture at the substrate andgenerating a foam. The polyurethane foam can be open-cell or closed-cellfoam, and in an exemplary embodiment is closed-cell foam. For example,closed-cell foam can exhibit enhanced moisture vapor retarder and airbarrier characteristics. An exemplary polyurethane spray foam andtechniques for applying such foam to a substrate are described in U.S.Pat. No. 7,160,930, the contents of which are herein incorporated byreference.

The layer of plastic foam can be of any thickness that is suitable forproviding an air barrier and optionally a barrier to moisture vapor. Forexample, the thickness of the plastic foam layer can be from about 0.5inch to about 10 inches, preferably from about 1 inch to about 6 inches.In one embodiment, the thickness of the plastic foam layer present in awall or deck is about 2 inches or less. The plastic foam can have anysuitable density for providing the desired insulation and barriercharacteristics. For example, in exemplary embodiments, an open-cellfoam can have a density of from about 0.3 to about 0.7 pcf, and aclosed-cell foam can have a density of from about 1.5 pcf to about 2.5pcf.

The plastic foam layer can include an optional primer coating present atits outer surface to enhance adhesion between the plastic foam layer andthe layer of a blown-in fiberglass insulation. When employed, theoptional primer coating constitutes a part of the plastic foam layer.For example, the primer coating composition can employ the same binderas that used in the blown-in insulation material. The primer coating canbe a substantially thin coating in comparison with the overall thicknessof the plastic foam layer.

A layer of a blown-in fiberglass insulation is formed above and incontact with the plastic foam layer, and can function as a thermaland/or acoustic insulation. In an exemplary embodiment, the layer ofblown-in fiberglass insulation substantially covers the entire layer ofplastic foam. The layer of blown-in fiberglass insulation is arranged onan interior side with respect to the layer of closed-cell polyurethanefoam. In the case where there will be access to a sealed attic, forexample, to performance maintenance on HVAC equipment present in theattic and/or to employ the attic as a storage area, the risk of fire inthe attic increases. In view of the increased fire risk, the blown-infiberglass insulation can function as an ignition barrier.

Suitable methods and systems for forming a blown-in fiberglassinsulation are described in U.S. Patent Application Publication No.2007/0234649, the contents of which are herein incorporated byreference. The use of blown-in fiberglass insulation can providesubstantial advantages over conventional fiberglass materials such asfiberglass batts, boards and blankets. For example, blown-in fiberglasscan facilitate the installation of insulation in and around irregularlyshaped cavities and structures which would normally be cumbersome tofill using conventional fiberglass mats. Additionally, the blown-infiberglass is can be substantially self-adhering to the plastic foamlayer, whereas the use of conventional fiberglass materials typicallynecessitates the use of pins, staples or other means for affixing sameto the plastic foam layer.

For example, particles of fibrous insulation can be blown using ablowing machine, and an aqueous binder mixture can be sprayed onto theparticles while in air suspension. A blowing machine that can be used,for example, is a Unisul VOLU-MATIC machine made by Unisul Company ofWinter Haven, Fla. The particles sprayed with binder can then bedirected into a cavity to form a thermal and/or acoustic insulation.

The fibrous insulation can be provided in any suitable shape and sizesuch as, for example, in the form of nodules and/or clumps. The averagediameter of the fibrous insulation particles can be, for example, fromabout 0.25 to about 1 inch, more preferably from about 0.25 to about0.375 inch. Nodules are relatively small diameter, fibrous insulationparticles of about 0.25 inch diameter and smaller. Clumps are defined asparticles having diameters greater than the diameter of nodules, and upto a conventional size of clumps in the blowing insulation industry, forexample, less than about 0.5 inch in diameter. The majority of clumpsand/or nodules are smaller than 0.5 inch in diameter, but larger sizescan be used. The clumps and/or nodules can be produced by runningmineral fiber insulation such as virgin fiber glass insulation or fiberglass insulation containing a cured binder through a hammer mill,slicing/dicing machine, or other device for reducing material to smallclumps and/or nodules as is common in the industry.

For example, the particles can be formed by passing virgin fiber orscrap resin bonded fiber product through a perforated plate in a hammermill. In addition to glass fibers, the insulation can include otherinorganic and/or mineral fibers such as, for example, mineral wool, slagwool or a ceramic fiber. The loose fill particles of fibrous insulationcan be made by running virgin fiber or fiber product scrap through aconventional hammer mill, a slicing/dicing apparatus, or an equivalentmaterial processing machine. A slicing/dicing apparatus cuts or shearsblankets of fibrous insulation into small cube like or other threedimensional pieces, while a hammer mill tears and shears virgin fiberglass or fiber glass blanket into pieces, collecting only pieces below apre-selected size through use of an exit screen containing the desiredhole size. Virgin fiber is a fiber web or blanket made specifically forspray insulation and typically contains no resin binder.

Any type of fibrous insulation product can be processed in a hammermill, e.g., fibrous blanket in which fibers, including glass fibers, arebonded together with a cured, usually thermoset resin, or a blanket ofvirgin fiberglass containing only de-dusting oil, silicone, anti-staticagent, etc. The binder used to bond glass fibers together in the blanketmay also contain one or more functional ingredients such as IR barrieragents, anti-static agents, anti-fungal agents, biocides, de-dustingagents, pigments, colorants, etc., which may be applied to the fiberseither before, or during processing in the hammer mill or other reducingdevice. The size of the hammer mill exit screen openings can be variedto produce the desired size of clumps and/or nodules. The typical sizeof exit screen openings range from about one half inch to about threeinches, for example, about 1 inch.

The clumps and/or nodules of mineral fiber such as fiberglass can alsoderive from what is called “virgin blowing wool.” This is achieved bymaking insulation fiber in a conventional manner except that no resin orbinder is applied to the fibers. Instead, only a conventional amount ofde-dusting oil and/or an anti-stat is applied to the fibers and theresultant fibrous blanket is then run through the hammer mill. Otheragents can also be applied to the fibers such as a fungicide, a biocide,filler particles and/or IR reflecting particles.

The fibers of the insulation can be of any suitable dimensions, forexample, such fibers can have an average diameter of about 2 microns orless. The average fiber diameter can be 6 microns or smaller, buttypically is less than about 3 microns or smaller, more typically about2 microns or smaller, and most typically 1.5 microns or smaller.

The particles of inorganic fibrous insulation can also containconventional amounts of one or more biocides, anti-static agents,de-dusting oils, hydrophobic agents such as a silicone, fire retardants,phase change material, particulate aerogel, coloring agents and IRblocking agents. The other additives, when present, are also preferablyincluded with the clumps or nodules.

To install thermal insulation using an aqueous adhesive, the aqueousadhesive can be supplied by the manufacturer at the proper concentrationwithout further mixing or dilution, or aqueous adhesive can be made upby adding the proper amount of water to a tank, and then adding theproper amount of a resin, preferably a concentrated solution of theresin, to the water in the tank while optionally stirring to insureproper mixing. If a powdered resin is used, more time and stirring willbe required to obtain a relatively homogenous solution. Also,particularly when the water in the tank is cool, it may be advantageousto heat the water to at least room temperature before adding the resin,or using a heated adhesive cart. Any suitable water-soluble resin can beused in the present method, such as a polyester resin, preferably ahydrolyzed polyester resin in concentrated solution in water, such as aconcentration of about 10 to 30%. The most typical resin for use in thepresent invention is a water-soluble, partially hydrolyzed polyesteroligomer such as SA-3915 available from Henkel Corporation ofGreenville, S.C. Another resin option is a polyvinyl alcohol resinavailable from Para-Chem Corporation, Simpsonville, S.C.

An adjustable-rate pump connected to the adhesive tank supplies theaqueous adhesive at the desired rate and pressure to spray jet(s)through one or more flexible hoses to properly coat the particles offibrous insulation with the desired amount of aqueous adhesive. Manydifferent types of spray jets can be used, and one that performs well isSpray Systems Co. 65 degree flat spray nozzle with an orifice sizeranging from 0067 to 0017 in capacity size.

The blown-in glass fiber insulation can have any density that issuitable for providing adequate insulation and ignition barriercharacteristics, for example, from about 0.8 to about 3.5 pcf, morepreferably from about 1.5 to about 2.5 pcf, more preferably about 1.8pcf. The blown-in glass fiber insulation layer can have any thicknessthat is suitable for providing adequate insulation and ignition barriercharacteristics, for example, at least about 1.5 inches, preferably atleast about 2 inches, and more preferably from about 2 inches to about14 inches.

The layer of a blown-in fiberglass insulation can, for example,substantially cover the layer of plastic foam. In an exemplaryembodiment, the layer of blown-in fiberglass insulation can be insubstantial contact with the plastic foam layer. As used herein, theterm “substantial contact” between the layer of blown-in fiberglassinsulation and plastic foam layer means that at least one contact pointexists between such layers in each square inch of area of the plasticfoam layer. In an exemplary embodiment, at least five contact pointsexist between such layers in each square inch of area of the plasticfoam layer. In an exemplary embodiment, in any areas where the layersare not in contact, for example, due to the substantially spherical orirregular shape of the particles constituting the blown-in fiberglassinsulation layer, the gaps present between the layers is about 0.125inch or less.

The layered configuration and substantial contact between the blown-infiberglass insulation and the plastic foam insulation layer can provideimproved ignition barrier characteristics. For example, installation ofbuilding materials in overhead spaces such as those existing in an atticcan give rise to unique challenges due to the non-uniform structures andcavities which are typically present in the attic, as well as the forceof gravity acting on the materials installed overhead. While not wishingto be bound to any particular theory, it is believed that suchsubstantial and intimate contact between the plastic foam layer and thelayer of blown-in fiberglass insulation can enhance or maintainadherence therebetween during a fire, which in turn can provideconsistent and improved ignition barrier characteristics of theinsulation system. In addition, the combined use of such layers canenable reduction of the thickness of the spray foam layer. Since sprayfoam is typically a relatively expensive material, this can contributeto reducing the overall cost of installing the insulation system. Thecombined use of plastic spray foam and blown-in fibrous insulationfacilitates installation of the insulation system in areas that aretypically challenging or problematic, such as overhead spaces in attics,bonus room floors present over garages, rim joists, cantilevered floors,etc.

The use of a blown-in glass fiber insulation can also provide theadvantage of reduced installation time and costs in comparison withemploying conventional glass fiber batts, boards and blankets. In anexemplary embodiment, the blown-in glass fiber insulation is adhered tothe plastic foam layer solely by the adhesive of the binder present inthe blown-in glass fiber insulation with the optional use of the primercoating of the plastic foam layer. In an exemplary embodiment, theblown-in glass fiber insulation is not mechanically attached to theplastic foam layer or the surrounding cavity structure. This can reduceinstallation time and costs and result in a more intimate contactbetween the blown-in glass fiber insulation and the plastic spray foamlayer.

Aspects of the present insulation systems and methods will now beillustrated and exemplified in greater detail with reference to thefollowing examples, but it will be understood that the invention is notnecessarily limited thereto.

EXAMPLES

Various comparative and exemplary insulation systems employing a sprayfoam layer and an ignition barrier layer thereon, were installed in asimulated attic/crawl space structure and tested in accordance with thestandard set forth in Southwest Research Institute (SwRI) Test Procedure05-01, “Test Method for the Evaluation of Polyurethane FoamSpray-Applied Onto Walls and Ceilings on an Attic/Crawl SpaceConfiguration,” which is also referred to as the SwRI-99-02 testcriteria. In such tests, a fire source was introduced in a corner of thesimulated attic/crawl space structure, and the time it takes for flamesto exit the front of the structure (flashover time) and the time ittakes for burn-through of the top surface of the plywood deck to occur(burn-through time) were measured.

The framing dimensions (walls and joists) of each of the examples is setforth in Table 1. Each of the examples employed a two componentpolyurethane spray foam having a density and thickness set forth inTable 1. Comparative examples 1 and 2 and Examples 4 and 5 employedwater-blown, 0.5 pcf polyurethane spray foam. Example 3 employed a 1.9pcf closed-cell spray foam.

Comparative Examples 1 and 2 employed conventional intumescent coatingsas ignition barriers. Comparative Example 1 employed Firefree 88intumescent coating available from International Fire Resistant Systems,Inc., and Example 2 employed Andek Fireguard intumescent coatingavailable from Andek Corp. Both intumescent coatings were applied usingan airless paint sprayer and the coatings were applied to the walls intwo coats. The first coat was applied in an amount of 1 gallon per 100sq. ft. and allowed to dry for two or more hours, and the second coatwas applied in an amount of 0.5 gallon per 100 sq. ft.

Examples 4 and 5 employed a blown-in glass fiber insulation as anignition barrier at a density of 1.8 pcf.

The flashover time (i.e., the time it takes for flames to exit the frontof the test structure) and burn-through time (i.e., the time it takesfor burn-through of the top surface of the plywood deck to occur) weremeasured for each example, and the results are shown in the followingTable 1.

TABLE 1 Example 1 Example 2 (comparative) (comparative) Example 3Example 4 Example 5 Framing (walls) 2 × 4 2 × 6 2 × 4 2 × 6 2 × 6Framing (joists) 2 × 8 2 × 12 2 × 8 2 × 12 2 × 12 Density of Spray 0.5pcf 0.5 pcf 1.9 pcf 0.5 pcf 0.5 pcf foam (walls) Thickness of 3.5 inches5.5 inches 1 inch 2 inches 2 inches Spray foam (walls) Thickness of 6.0inches 10 inches 2 inches 2 inches 8 inches Spray foam (deck) Ignitionbarrier Firefree 88 Andek Fireguard Blown-in Blown-in Blown-inintumescent intumescent glass fiber glass fiber glass fiber coatingcoating insulation insulation insulation Ignition barrier 1.5 gal per100 sq. ft. 1.5 gal per 100 sq. ft. 2.5 inches 3.5 inches 3.5 inchesamount (walls) Ignition barrier None None 4 inches 8 inches 2 inchesamount (deck) Estimated R-13 R-20 R-16 R-22 R-22 Insulation R- value(walls) Estimated R-21 R-36 R-29 R-41 R-37 Insulation R- value (deck)Flashover time 2:58 2:06 4:57 6:24 5:54 Burn-through 10.48 10:29 15:5616:09 >20:00 time

As can be seen from the test results, use of the glass fiber insulationmaterial in Examples 3 to 5 provided improved flashover time andburn-through time characteristics in comparison with the comparativeexamples. As well, employing the blown-in glass fiber insulation enabledthe thickness of the spray foam layer to be reduced while achievingcomparable insulation performance. The reduction of spray foam usage cancontribute to reduced insulation materials costs.

Exemplary insulation systems were also subjected to testing under theASTM E-84 tunnel test. Examples A to C employed differing types andamounts of insulation materials as shown in the following Table 2, andthe results of the ASTM E-84 tunnel test are set forth in such table.

TABLE 2 Flame Spread/ Insulation material(s) Smoke Developed Example Aopen cell polyurethane spray foam (5 inch thick, 0.5 pcf) 25/550 (comp.)Example B open cell polyurethane spray foam (5 inch thick, 0.5 15/625(comp.) pcf), painted with Firefree 88 (1.5 gallon per 100 sq. ft.)Example C open cell polyurethane spray foam (3 inch thick, 0.5 10/20 pcf), covered with blown-in fiberglass insulation (2 inch thick, 1.8pcf)

The above test results show that Example C, which employed apolyurethane spray foam layer in combination with a blow-in fiberglassinsulation layer, achieved flame spread/smoke developed characteristicswhich are significantly lower than those achieved by comparativeExamples A and B.

1. An insulation system for a cavity of a building structure,comprising: a layer of plastic foam insulation present on a substrate ofthe cavity, and a layer of blown-in fiberglass insulation in substantialcontact with the layer of plastic foam insulation, wherein the layer ofplastic foam insulation is present between the substrate and the layerof blown-in fiberglass insulation.
 2. The insulation system of claim 1,wherein the plastic foam is a polyurethane spray foam.
 3. The insulationsystem of claim 1, wherein the thickness of the layer of plastic foaminsulation is from about 0.5 inch to about 10 inches.
 4. The insulationsystem of claim 1, wherein the thickness of the layer of blown-infiberglass insulation is from about 1.5 inch to about 15 inches.
 5. Theinsulation system of claim 1, wherein the density of the layer ofblown-in fiberglass insulation is from about 1.5 pcf to about 2.5 pcf.6. The insulation system of claim 1, wherein the layer of blow-infiberglass insulation is left exposed and constitutes the outermostlayer of the system.
 7. The insulation system of claim 1, wherein thelayer of plastic foam insulation further comprises a primer coating onits outer surface for enhancing adhesion to the layer of blown-infiberglass insulation.
 8. The insulation system of claim 1, wherein thesystem is present in an attic of a building structure.
 9. The insulationsystem of claim 1, wherein the layer of blown-in fiberglass insulationis adhered to the layer of plastic foam insulation by a chemicaladhesive.
 10. A method of insulating a cavity of a building structure,comprising: forming a layer of plastic foam insulation on a substrate ofthe cavity, and forming a layer of blown-in fiberglass insulation suchthat the layer of blown-in fiberglass insulation is in substantialcontact with the layer of plastic foam insulation, wherein the layer ofblown-in fiberglass insulation is arranged at an interior side withrespect to the layer of plastic foam insulation.
 11. The method of claim10, wherein the plastic foam is a polyurethane spray foam.
 12. Themethod of claim 10, wherein the thickness of the layer of plastic foaminsulation is from about 0.5 inch to about 10 inches.
 13. The method ofclaim 10, wherein the thickness of the layer of blown-in fiberglassinsulation is from about 1.5 inch to about 15 inches.
 14. The method ofclaim 10, wherein the density of the layer of blown-in fiberglassinsulation is from about 1.5 pcf to about 2.5 pcf.
 15. The method ofclaim 10, wherein the layer of blow-in fiberglass insulation is leftexposed and constitutes the outermost layer of the system.
 16. Themethod of claim 10, wherein the layer of plastic foam insulation furthercomprises a primer coating on its outer surface for enhancing adhesionto the layer of blown-in fiberglass insulation.
 17. The method of claim10, wherein the system is present in an attic of a building structure.18. The method of claim 10, wherein the layer of blown-in fiberglassinsulation is adhered to the layer of plastic foam insulation by achemical adhesive.